Rubber tube



June 2, 1931.

E. HOPKINSON VET AL RUBBER TUBE Filed June 23, 1925 fw.. WMF

Patented June 2, 1931 UNITED STATES PATENT yorifice ERNEST OPKNSON, OFNEW' YORK, AND W-ILLIS 'A ,GIBBON 0F LITTLE NECK, LONG ISLAND, NEW YORK,ASSIGNORS TO MORGAN S5 A CORPORATION or MICHIGAN RUBBER TUBE' originalapplication lledirmie 23, 1925, serial No. 38,966. Diviaea'and'uiisappliation filed october lo,

This invention relates to the manufacture of hollow rubber articles, andmore particularly tubes in the form of, a complete annulus such as innertubes used with pneumatic casings in Yordinary motor vehicles. Thepresent application is a division of our application Serial No.' 38,966,filed June 23, 1925.

In the manufacture of inner tubes, by way-of illustration, it isgenerally the practice today to roll the calendered stock around two andone-half or three and onehalf convolutions about a pole or mandrel, tothen tape the ends `and/or the body of the tube so as to confinethestock under more or less pressure, then vulcanize the tubes, and aft-erstripping from' the pole splice the ends together. This old practicerequires the use of rubber composition that has been through many andcostly processes including coagulation, washing, breaking down,compounding, calendering, etc. i

The present invention contemplates the direct manufacture of inner tubesand similar articles, in the Yshape of the completed article, from latexor otheraqueous dispersions of rubber. It aims to produce a tube withimproved qualities and more cheaply than any heretoforev manufactured. pIt aims to obviate all splicing andother operations required where forinstance innertubes are firstmade in straight or incomplete annular formand the .free ends subsequently united to complete the article.y Itinsures the production of a tubewithout inherent unequal tensions likelyto cause canting of the valve stem, heretofore veXatious to automobilemanufacturers in their assemblage of tubes and casings. It also aims toavoid undesired inequalities in wall thickness such as caused by theprior art use of cross wrappers during vulcanization. These are someofthe advantages of the invention. Others'will appear in connection withthe detailed description following.

With the preferred embodiment of the invention in mind, and withoutintention to limit its scope more than isrequired by the y Serial No.311,462.

mittingthe passage of water and preventing the passage of yrubber andleaving thereon a deposit of rubber', out'of porous materials such asunglazedlporous non-vitreous earthenware or fibrous materials, anddepositing insoluble constituents from a water dispersion of rubberthereon in the desired formation and of a desired Wall thicknessdirectly fromthe dispersion, drying the rubber or rubber compound sodeposited, and ultimately completely vulcanizingthe deposit. Thedispersion may be a'natural latex having a natural, decreased orincreased rubber content, and if desired partially or completelyvulcanized; or there may be used an artificial latex formed by making adispersion of any suitable solid unvulcanized or vulcanized rubber. Thelatex may be, and preferably is, compounded toyield a rubber compositionhaving suitable strength, vresistance to abrasion', and other qualitiesrequisite to satisfy the requirements of the finished product. The termlatex is therefore employed in the claims with the above definition inmind. The latex is also preferably treated in such manner that'its watercontent may be more readily withdrawn and its insoluble constituentswill more readily deposit from the dispersion onto the desired waterpermeable form. After drying the deposited thickness of rubber may-bestripped from the porous form .or fabricwhich is preferably coated withstarch or other adhesion preventing agent to facilitate stripping ofthe` rubber from the mold. l

For a detailed ,disclosure ofthe nature and objects of the inventionreference is had to the accompanying specication and drawingsillustrating apparatus for carrying out an embodiment of the invention,in which drawings, Q

' Fig. l is a brokenl sectional perspective showing an embodiment ofapparatus for making an inner tube in a complete annular or jointlessform; i

Fig. 2 is across section through the form and deposit;

Fig. 3 is a broken awayA detail view; and

Fig.1 4I is sectional View .0f a laten supply gnelIIS. 'A v WRIGHT, orDETROIT, MICIIIGAN,

In the making of an endless tube by the present process, an endless form1 is provided, which may be of any suitable Water permeable material,that shown in the drawings being made with inner and outer fabric layers2 and 3 having an interposed filler 4 of iibrcus material. This fillermay be gradually reduced in thickness from the outer to the innerperiphery of the forni and at its inner periphery the fabric layers areextended radially inwardly to form flapsas shown at 5. Over these flapssuitable washers or rings 6 of felt or similar material are disposed,and the flaps and felt rings are Y Y, brought into and out of registrywith the channel 10 for a purpose to be later described. The sleeve 11is provided with. a flange 14 bymeans of which it may be convenientlyturned. The tube 9 has its lower end spaced Vfrom the inner wall of theform 1 a distance slightly greater than the thickness of depositdesired. At its outer end the tube 9 is connected to a pipe 15 leadinginto a T 16, and leading from a secondY opening in the T is a pipe 17vcontrolled by a valve 18, the pipe having a quick detachable connection19 with an air or other gaseous fluid supply pipe 20. Alsoflead-ing fromthe T 16 is a pipe 21 provided with a valve 22 and having a quickdetachable connection 23 with a 'latex supply vpipe 24. The pipe 24 isprovided with a valve 25 4) and leads into latex tank 26 provided with asight gauge 27. rIhe tank is also provided with a filling inlet 28controlled by a' valve 29. Leading from the upper part of the latex tankis a pipe 30 connected to a cross coupling 31, into an arm of which avalved pipe 32 leads, this pipe being connected with any suitable meansorproducing a. vacuum. )Also leading Vinto the coupling 31 is a valvecontrolled vent pipe 33. Thereinaining arm oi the coupling is connectedto a valve controlled pipe 34 for supplying air or other gaseousmedium'.

In operation the tank 26 is `first iilled with latex, and this latex, asbefore stated, is preferably treated in such manner as to' increase itsilterability, that is, to cause it to depositits rubber and any addedcompounding constituents at a greatly increased-rate on the surface of apermeable material with which it may be in Contact. Examples of themanner in which this increased iilterability may beobtained are given asfollows, but it is obvious that any other suitable Lsoaaae means forobtaining the desired result may be obtained.

Ordinary ammonia preserved latex is freed of its ammonia content and tothe. latex is the-n added 1/2% phenolv and .06% trisodium phosphate.YUsing the above treated latex the following compound is'then made up;

In mixing the above com-pound the various ingredients added to the latexare all incorporated in the form of emulsions. The zinc oxide andsulphur are vmixed with water to make a thick mush and then added to aVwater solution of glue and run througha paint mixer. The oxy normalbutyl thiocarbonic acid disulphide is mixed in some solvent naphtha andthen emulsiied with a Watersolutionofglueto which a small amount ofsodium oleate has been added. The dibenz'lamine is emulsified'in thesaine manner as theV oxy normal butyl thiocarbonic acid disulphide.After mixing up the compound it is allowed to stand at room temperaturefor about one month. At the end of this time such a mixture isvulcanized, thickens somewhat, and its lilterability isl markedly in-`creased. For example when iiltered through fabric such as underwriterslhose fabric the vulcanized latex gave a deposit of .082 inchesovernight. Theabove illustrates one method of increasing Lilterabilityof vlatex by vulc'anization in a specific manner;

Y Another example in which latex is' treated to increase itslterabil'ity is as follows: Latex is first treated to removeav largepart of its water soluble constituents and the following compoundthenmade up r The llers are added in the form of a` Water paste andenough concentrated am! monia lis added to the mix to make 1% of theammonia. t a total of 145 parts water. Such a. compounded latex in twohours deposited a-layer .069

inches thick. In this ca'se the ilterability oi latex is increased bythe addition of fillers. Y At the start ofthe operation, the valve inpipe'32 is first opened and a`vacuum applied to withdraw air A :fromthebody of the latex.

Enough water is added tomakeA The valve in pipe 32 is then closed andthose in pipes 34, 24 and 2l are opened, and by reason of the airpressure thus introduced on top of the body of latex in tank 26, thelatex is forced into the form .l under pressure. The form at this timemay be vertically disposed as shown in Fig.. 3, and as the latex entersthe form, the air therein escapes through the interstices of the form,and if desired its escape may be assisted by inserting in the top of theouter periphery a hypodermic needle 35. The Water and water solubleconstituents of the latex then pass through the form to its exterior,leaving on the interior Wall of the form a deposit 36 of the solidsuspended constituents of the latex. The supply of latex under pressureis kept up until the desiredthickness of deposit has been obtained whenthe supply is shut off, the valve 22 closed, and the coupling 23disconnected, after which the position of the form and deposited tube 36is reversed, that is, the part of the form containing tube 9 is broughtto the top with the end of the tube pointing upwardly. A small charge ofcompressed air under light pressure may then be introduced, after whichthe form is again brought to the position shown in Fig. 3 When thecharge of air with the assistance of gravity will force out the unusedlatex through the tube 9 and pipe 21, the valve 22 being opened at thistime. After the form has been emptied, the valve 22 is again closed, thesleeve 11 rotated to bring its openings 12 and 13 in registry with thechannel 10 and heated air or other drying medium is supplied through thepipe 20, this air entering the form through the tube 9 and beingexhausted therefrom by way of the channel l0. After the drying or dryingand vulcanizing is completed the clamps 7 may be removed andthe tube 36taken'out. Instead of removing unused lateX in the above manner, theform may be kept in the position shown in Fig. 3 and air introduced atthe top through the hypodermic needle 35. After completion of theoperation, the needle is removed and the freshly laid down deposit 36immediately closes the opening formed by the needle. It can readily bedetermined when the desired thickness of the deposit 36 has beenobtained by noting on the sight glas 27 the amount of latex which hasbeen use If a vulcanized latex has been used, the tube making operationis completed upon the drying of the lateX deposit, and all that isnecessary is to open the form l and remove the tube. Preferably the formbefore use is coated on its interior wall with starch or other adhesionpreventative. If an unvulcanized latex has been used, this may becompounded in such manner that vulcanization may be accomplished eitherby the ordinary heat cure or by vulcanization at lower temperatures.When the form used contains fabric', there may be a tendency to shrinkand collapse during the drying, but allowance may be made for theshrinkage, and by drying under heat and maintaining closed the valvedconnections, the air Within the tube 36 becomes heated and expands andsome steam 'is generate-d from the moisture by the drying heat, with theresult that sufhcient pressure is maintained within the tubular deposit36 to prevent collapsing. Or, prio-rte heating, or during heating, airunder slight pressure may be introduced to prevent collapsing and unduevshrinkage. The pressure differentialduring the various operations notonly. prevents collapse but it aids deposition. Any other suitable meansfor providing a pressure differential may be used. In the commercialapplication of the method, -it is of course, obvious that a large numberof forms will be operated upon at,

the same time. It will be seen that by the use of our method as abovedescribed, an inner 'tube may be made without any joint and which has noundesired inequalities in thickness.

When making inner tubes by the use of our process the so-called valvepatch or valve stem reinforcement of fabric may be incorporated in anysuitable manner, for

instance during the formation of the tube or by external application ata later sta-ge.

While specific examples of the method Y have been given and specicapparatus for carrying out the method have been illustrated it isobvious that it is not limited in its application and may be used forforming a wide variety of articles and .with the use of various types ofapparatus for carrying it out. While in the examples given forms offibrous material have been illustrated and described, any other suitablepermeable material may be used, and a choice of such materials willoften depend upon their adaptability for use in making any particulardesired article.

Hav-ting thus described our invention, what we claim and desire toprotect by Letters Patent is:

l. The method of making tubular articles in a complete annulus whichcomprises supplying an aqueous dispersion of rubber to the interior' ofa water permeable hollow annular form, depositing suspended solids fromsaid dispersion on the form by withdrawing aqueous matter from thedispersion through said form, drying the deposit, a pressuredifferential being maintained on opposite sides of the form during saidoperations, and removing the article.

2. The method of making tubular articles which comprises, supplyingrubber latex under pressure to the interior of a water permeable hollowannular form, de ositing suspended solids from the latex on t e form bywithdrawing aqueous matter from the latex through said form,rwithdrawing `unused latex and drying the deposit while maintainingpressure on the interior ofthe form, and removing the article. 3.' Themethod of making tubular articles in a complete annulus which comprises,supplying rubber latex, tre-ated to increase its filterability, underpressure to the interior l@ of a water permeable hollow annular form,depositing suspended solids from said latex on the form by withdrawingaqueous matterfrom the latex through the form, withdrawing unused latexand drying and vul- 15 canizing rthe deposit while maintaining pressureon the interior of the form, and removing the article. A

Signed at New York, New York, this 4th day of October, 1928. Y y 2oERNEST HOPKINSON.

Signed at New York, New York, this 5th day-of October, 1928.

WILLIS A. GIBBONS.

